Machine or rapid-fire gun or the like



Sept. l, 1925.

c. POHLMANN MACHINE OR RAPID FIRE GUNy OR 'XI-IE` LIKE i 4 Sheets-Sheet l Filed March 27. 1924 s, v 1 nu u Q .n a 1n 1n q r m i Ir l .I

I INV ENTOR Chrrl'aj tra n H671 [1f/al1 11,

BY ....L

-\'1'TORNF\ N N A M L H P C WINE 0H RAPID FIRE GUN 0R THE LIKEv 4 Sheets-Sheet 2 INVENTOR Chrn'an Pl'hlmnn Filed March 27.

MYX

ATTORN liY Sep`t, l, l925f C. PHLMANN- MACHINE OR RAPID FIRE GUN lOR THE LIKE Filed March 27, 1924 4 Sheets-Sheet 3 u INVENTOR Christ/an Pahbnann Sept. l', 1925.

C. PHLMANN CHINE OR RAPID FIRE- GUN 0R THE [QI-'KE Filed March 27, 1924 4 Sheets-Shut;

.Ill

"INVENTOR @Mimizan/12mm,

BY ATTORNEY ntented Sept. l, 1925.

UNITED STATES PATENT OFFICE.

:naIs'rnN PHLMANN, or auesnua'e, amm, AssIeNoa or oma-mlm' To in anum Bno'rnnas, me., or NEW Yoan, N. Y., A coaromriou or imw Yoan.

MACHINE B RAPID-FIRE GUN )B THE LIKE.

A1I1 11eati|'.ll1l led Hatch 27, 1924. A Serial I0. 708,828.

7 all whom 'it may concern.:

Be it known that I, CHRISTIAN Pm.- aNN, a citizen of German residing at lurstrasse 35, Augsbur ermany, ave vented certain new an useful Improveents in Machine or Rapid-Fire Guns or e like, of which the following is a specization.

It is well known, that in machineorV .pid-fireguns, and the like, prolonged .pid firing has heretofore only been posble with water-cooled guns. Water-coolg, however, has man serious disadvanges, such as necessitating carrying cooling ater in the gun jacket, and in reserve res- Ivoirs, requiring much time and great ex 'tions for replenishing the necessary cool-Iy 1g water supply, sometimes from great lstance and at great danger. Steam being roduced in rolonged action furthermore :poses positlons, increasing the danger of andling the gun. On the other hand, if 1e guns are 1dle for long periods during )1d weather, the water may freeze, getting 1e gun out of order. For these and other nown reasons, particularly where local )nditions make it necessary, air-cooled uns are used to a considerable extent, fir- 1g being necessarily much slower if connued firing is requlred, or otherwise long eriods for cooling-off being necessary, after short series of rapidly fired shots. Neverieless, in cases where it is very diicult r' impossible to get cooling-water, and 'here guns must be used in dry or diicult grritory, the air-cooled system is superior i the water-cooled system. In aeroplanes. 'here ra id firing occurs but only short aries of s ot's are being red, the air-cooled ystem is very eiicient.

My invention constitutes a decided prog-i ess over both, water-cooled and air-cooled Vstems, inasmuch as it permits as rapid nd even more prolonged firing as with yeter-cooled guns or riiies, without having lany of the disadvantages connected with lle latter, being inde endent of local conitions, always ready or instant use, always iaintaining its maximum efficiency, requirng n'o moving and replenishing of water, eing ca able of more continuous use, hanled an moved more easily and rapidly.

permitting concentration solely on firing creased, because the air, traveling past the rifieor gun-barrel at a higher speed, absorbs less heat per unit of air, than if trav eling at a lower speed. In other words, the volume of cooling-air must increase much faster than the number of shots being fired during a given period of time. Applicants researches roved, that if a plurality of successively p acedand properly designed gas or air e]ector nozzles are used, and are properly arranged, adjoiningly to the outlet of the barrel, the suction and speed of the cooling-air currents, beingproduced by the exhaust powder gases, assing through the nozzles, increases conslderabl faster than the number of shots being red within a given period of time. This having been proven, the limit of the rapidity at which shots-can successively be red for prolonged periods, depends mainly on the speed at which heat may be transmitted from the inner surface to the outer surface of the barrel. The necessity and difficulty of conducting the heat, in this manner, has also been partly overcome by applicant, by creating a strong suction at the barrel outlet, at the moment the lock is opened,whi1e the used cartridge is taken out., and during reloading, thus producing cooling-air cur-v rents within the barrel, cooling the latter internally and cleaning it of powder gases. In order to make full use oi this improved cooling device, applicant had to produce a new device, for greatly increasing recoil, whichvenables reloading 'the rifle or gun as fast as firing is permitted bythe improve air-cooling.

The novel and original features `of my air-cooling and of my improved recoil device, which, combined, are necessary, in

order to get the greatest results, will be fully described and explained on hand of my drawings, which show a few designs.

Y 45v tube, for coolingair currents-along powlillgeasesas will later on be more fully which may be varied considerably, in view of the broad principles involved in my invention. p y

Referring now to the attached drawings,

6 Fig.` 1 shows a longitudinal section through` va art of m riiie or gun. Fig. 2 shows a longitudinl section of another design,

containing my improved recoil mechanism.

Figs. 3 and 4 show resplectively on a somewhat larger scale, the ont portion of the barrel and ejector nozzles in combination with my recoil mechanism in respective sitions, immediatel before and after a s ot has been fired. Figs. 5 to 8 show respectively cross-sections of diiferent designs of my recoil mechanism; Fig. 9 shows in crossl section a fportion of the barrel with another design o the recoil 'mechanism Fig.,` 10

Agiim shows a dierent design as shown in igures 3 and 4, the nozzles being made in separate sections and being screwed toigetlier. 11 to 14 are cross-sections of various designs showing vimproved features in the design o conductors and of bearings a5 or supports for barrel and conductor, and

showing means for cooling the gun-chest and rear bearing for the barrel, etc.

Referring now moreparticulai'ly to Fig.

1, 1 represents a rieor gun-barrel, 2, 3, 4

are tively ejector nozzles, 5 is a conically aped expansionnozzle, being shown herein as extension of nozzle 4. 7 represents an outer casing or cover. The ejector nozzles may all be connected to ther by webs,

85 as shown herein. 6 are we which may support the nozzles within the outer cover 7.

1 isfa rear portion of the barrel, .which is thickened, 9 is a bearing for the rear end of the barrel, which bearing may be s part of the outer cover 7, as shown herein. 10 indicate inlets, permitting air to enter into a 'thin the cover 7. 11 represents which latter may be one piece e barrel. 12 is an air conductoror .thebarre,aswillbe e lainedlatercn, coo 4 -air being. brought into close contact with barrel and webs. 13 and 14, re-

permitting coo -air currents to enter into i the space being rmed between conductor 12-and cover 7, for isolating and cooling the outer cover 7, the air afterwards through holes 14. The outer cover may this wfpwtively, are s howing additional air holes,

, unexplained more funyimron. Afm

vand for the barrel.

lavillgcreased ther ob'ect of the1 e ansion izzle, is,d t1 grdii eanteoutru ingpowei gases, inordxi' to deaden'the sound of th exhaust powder gases as much as possible.

Referring now to Figure 2, the same num bers apply to similar parts, as before, tlu design vary' y however, in ,importan points, asv will fully explained.V 17 rep resen'ts a thickened end portion of the bar rel, be shown herein as one piecewitl the ball'i'l, but which may be screwed onti the latter. 18 indicates a ring shaped spec between part 17 and the outer cylindrica surface of the ejector nozzle 2. 19 indi cates the face of part 17. 22 may be exten sions of the webs, which connect the nozzle: 2 and 3, being so arranged that the exten sionsl form bearings or supports for part 11 The webs 11 on thi barrel are shown herein to run s irally an( the pitch may increase towards t e forwar( end of the barrel. The conductor 12 is o: a larger diameter at vits rear end, bein; taper and having .gradually decreaing .di ameter in forward direction. The purpos being to increase the velocity of the ai] gradually from the air inlet end. The web@ may or may not nach up to part 17. Th1 expansion nozzle 5, shows several opening 33, whereby it may act in a double-capacit] of ejector nozzle and expansion nozzle. Fig 2 further shows my` improved device for re coil which will be fully explained on hancl of .3 and L ReferringV now to Fi 3 an 4, Fig. i showsa rtion of the gfiiirward end of thi vbarrel an conductor and the e'ector nozzles my recoil device, ebarrel and member 1 being-in their 'tion of rest If 'a shot is being fired, the arrel and-member 17 are thrown backwards into. the position shown in Fig. 4,. through momentary pressure which is being created within nozzle or member 2, through the exhaust soon as the back pressure is re ved,. the barrel and member 17 are quickly thrown in forward direction into lthe position of rest by means of a spring. By selecting the opening of the nozzle 2, greateror smaller, the back pressure of the exhaust powder ses may he deor increased, alt will,1lthereby di; cleasingor increasing t e reco' as may dered. A werful means is thus being created, whi enables to load or reload the gun as fast as desired2 or as fast as the cool-l vmg device may permit. This will be lateion more explained. v The object of the ejector nozzls, 3, 4, and nozzle 5, as shown in Figs. 3, and 4, is to create a stron suction ofcooling air, through the action 0 the exhaust wder gases, similarly as explained hereto ore in connection with F' 1, while the gases are rushing through tige nozzles,

after a shot has been fired. It will be seen from Fig. 3, that in its position of rest, the member 17 closes nozzle 2, preventing air from flowing through nozzle 2, the air moi mentarily flowing only through nozzles 3, 4

and 5, as indicated by thin lines and arrows. A moment after a shot has been fired, the barrel andmember 17 as explained, are thrown towards the right, in position as lo shownin Fig. 4, whereupon the member or nozzle 2 is open to cooling air currents, the latter cooling the nozzle 2 now also from within and at the same time creatingv a strong suction at the barrel outlet, thereby sucking cooling air through the barrel, cooling the latter also from within and cleaning it of powder gases, because the lock is opened at that moment and the spent car-- tridge is automatically removed, before the 20 gun is being automatically reloaded, which may all be accomplished within a small fraction of a second. The barrel and mem.

ber 17 are quickly thrown back again, into their position of rest (Fig. 3) by means of 26 a spring, which need not be shown. Immediately after the barrel has reached its position of rest, the next shot is being fired and the same series of -motions or actions are re ated, andsoon., The greater the rapidity 30 .o the shots, the more steady andV permanent becomes the flow of the cooling air, on account of the great momentum of the stream of cooling air, which latter moves at an exceedingly high velocity, the air being sucked in through openings 10 (Figs. 1 and 2) and through conductor 12, passing out through the nozzles into the open air, as clearly indicated by thin lines and arrows, see Figs. 3 and 4, theheavy line and arrow representing the direction of fiow of the exhaust powder gases. Thin dotted lines and arrows, replresent leakage of gases at the moment ex aust powder gases are partly stowed or penned up within the nozzle 2 and before the barrel and member 17 have been thrown towards right. It will be seen, that the gases, leaking out betweenV members `2 and 17,' are directed forwardly, into nozzle 3, carrying with them additional air instead of disturbing the steady'flow of cooling air.

It will be noted, that the openings 33, being i rovided within the expansion nozzie 5, also ave the purpose, after the exhaust powder gases have passed out,l to permit cooling air to flow out at the forward end of the nozzle 50 As previously explained, air is alsobeing i sucked in through holes 13 in the outer cover 7, and through the annular space being provided between the conductor and the outer cover, heat-insulating the latter and keeping G5 it cool during action, at the same time cooling the conductor from without. Figs. 5 to 8 show different designs of the two members of my improved recoil mechanism cooperating in producing increased recoil; Figs. 7 and Bare showing the end surface of the part 17, rilled or broken, as will later on be better explained.

Fig. 9 shows a different design o f my recoil mechanism, wherein tlie ejector nozzles are arranged inovably,` instead of being stationary, as in previous designs, the principle of the recoil device remaining the same as before.

24 represents herein a dish or plate, being a par;l of the ejector no zzle 4; 32 is a spring, for returning thel nozzles'to their posi-.ion of rest after each shot; 26 is a thickened part of the outer cover 7, having a sliding surface for the dish 24. 25 is an adjustable sleeve or nut, being screwed into the outer cover and having asliding surface for the forward end of the nozzles; 29 is aslot iii the sleeve; 28 is a block;27 being a threaded end of said block, the latter being screwed into the expansion nozzle 5. The block 28 being arranged slidable within the sleeve 25, within the limit of the slot, the latter forming a stop for the block, both in the position of rest and limiting forward motion of the block and nozzles during a shot. Normally, the block is resting against the inward surface of the/slot as shown, the sleeve 25 forming at the same time a lirm rest or thrust bearing for one end ofthe spring 32, the other end of the spring resting against the movable dish 24, the later being a part of the nozzles as explained before, moving with the 'same when a shot is being fired. 30 is a turnable pin, being carried byone end of said block. 31 is a rod .or shaft, being suspended on and operated by the pin 30, the' rod o erating in turn a loading mechanism of t e gun in known manner. It will be seen that air-cooling has also been shown around the expansion nozzle 5 and air o en ings are provided at or near the end o the nozzle in order to produce `both cooling and a more steady stream of air, whereby also the spring is cooled.

Fig. 10 shows a design wherein the nozzles are stationary and wherein only the barrel and the member of the recoil mechanism, which is attached to the barrel, are movable. The nozzles are shown herein separatelv, demountably, or exchangeably, be-

ing adapted to be taken a art or assembled by means of threaded en s, which `make it possible to carefully finish or polish each nozzle, in order to obtain the greatest eiliciency, and which also permits to exchange nozzle 2, which latter, as explained heretofore, controls the speed at which the recoil mechanism may operate the .reloading mechanism. It is advisable to make nozzle 2 of material which is verystrong and can withstand great heat, while nozzles 3, 4, and 5 may be of aluminum in order to make them light and good heat conductors.

Fig. 11 shows a design wherein the barrel and the nozzles arestationary and wherein the conductor 12 and thegas ejector nozzles are made in one piece, being screwed into the outer cover 7 atjts forward end and being preferably supported near its middle portion, in the outer cover. 41 is a cooling sleeve, surrounding the barrel, 11 being cooling webs on the sleeve, the sleeve and webs, forming one part with the conductor, some of the webs being extended, servin as means for connecting the nozzles an the conductor, as shown herein. By unscrewing the nozzles at their forward end, the nozzles and conductor may easily be taken out of the outer cover; 42 shows a riileor gun-chest, the outercover 7 being fastened to the chest in any known manner, so that it may easily be demountable, together with the conductor and air nozzle, making it ossible to quickly replace the barrel, i it should become necessary to do so. 43 and 44 represent openings, the latter being adapted for permitting cooling air to be sucked in, in sulicient quantity to cool the rilleor gun-chest and the bearings of the barrel, the air being drawn into the cooling or gun-c est, the webs connecting y the nozzles being preferably arranged within a plane with the webs of the conductor, after being assembled.

Fig. 13 represents a design wherein my improved recoil device is employed in different manner as explained before, the conductor 12 being one piece with the members 17 of the recoil device and beingY firmly arranged on the barrel and moving together with the latter during or immediately after each shot. It will be noted that the conductor has taper holes in portions towards the rear and front ends, the conductor being fitted to the barrel at these taper holes, a cylindrically shaped portion of the hole within the conductor being slightly larger in diameter than they respective barrel diameter, though the difference in the respective diameters is very slight and need not be shown herein. 42 again shows the rifleor gun-chest and 43 and 44 show respectively air inlet and outlet holes, for air-cooling purposes, similarly as shown in Fig. 11. 22 shows continuations of webs 6, 'serving as supports for 'the member 17 of the recoil device and of the conductor. The outer cover 7 and the nozzles, which latter may again be screwed into the cover, may be space arranged between the cover 7 andthe/taken oi together if desired, whereupon the conductor, additional cooling air entering throu h openings 10. By regulating the size o openings 10, 43 and 44 the air currents may be regulated. It will be noted, that the conductor has been greatly shortened and has been arranged close to the nozzles, directing the coolin air closer towards the nozzles. Iny or er to revent swelling ofthe barrel causi Y trou le, in taking the gun apart, the cy drical hole within the'` sleeve may be slightly larger in diameter than the barrel, the latter being supported within the sleeve and centered therein by a short taper hole, as shown.

Fig. 12 shows a design, wherein the barrel and nozzles again are stationary and wherein the rear end of the conductor is formed in such manner, that the cooling air, which isV sucked into openings 10 at very high speed, is directed forwardly with as little whirling, and as little loss of speed 1s possible, the outer part of the conductor, as shown, having a long cylindrical shape, a ring shaped s ace being arranged between the outer sur ace of the conductor and the outer cover'V 7, air holes 13 being rovided within the outer cover 7, similary as in Figs. 1 to v4, for cooling air to be sucked in, an principally, for keeping the outer cover cool, similarl as in previous designs. It will be not that the nozzles are herein formi a separate part, the latter being screw into the forward end of the outer cover; in such manner, that the .conductor conductor may be taken off and ,the barrel replaced,.if required. Fig. 14 differs from Fig. 13, mainly, in the manner in which the member 17 and conductor 12 are supported at their forward end, within the outer cover 7, being guided by, and sliding within a large round bearing, the latter being provided within the outer cover.

From the di'erent drawings it will be seen, that the barrel and conductor, as well as the nozzles have many cooling webs, olfering a large cooling surface, the vwebs, being not in direct'contactgwith the outer cover, but adapted to absorb the heat from the barrel andy conductor and nozzles, the heat being in turn absorbed by the cooling air currents, the latter being. produced by the exhaust powder gases. There are as few contact surfaces provided between the conductor and nozzles respectively, and the outer cover, as possible, the object being to keep the outer cover cool, so that it may be easily handled at any time, and loaded on horses or carriedby men, if necessary, and also to prevent heat or hot air currents from the outer cover to cause scintillating or flickering which latter would make accurate aim impossible. For these reasons, heat insulating mater'al may be inserted, wherever contact is" unavoidable between the inner hot parts and the Vouter cover. Y

Suction openings, similar to openings 33, shown, vhave been used before in expansion nozzles, on rapid-fire-guns or the like. for instance in Brit-ish Patent No. 12,227 of 1910, but such expansion nozzles and the openings mentioned have not been used in connection with one or more compression and expansion nozzles, that is, in combination with a nozzle or nozzles, wherein exhaust-powdergases are expanded, while cooling-air is simultaneously being compressed within the same nozzle, as is the case within gas ejector nozzles 3 and 4. According to the British patent, such slots within the expansion noz zle, should do all of the required suction of cooling air, which it is not capable of doing. These slots assist somewhat in producing suction of cooling-air and in producing a more steady flow of cooling-air, as explained hereinbefore. They also assist in kee ing the outer cover cool, but they cannot a one provide a successful air-cooling system for rapid-re-guns or the like.

I will now more fully describe the action of my device or combination of devices. After each shot, following the projectile', exhaust-powder-gases are rushing with tremendous velocity, through ejector nozzles 2, 3, 4and nozzle 5,- and as a result of friction between the gases and the air, the latter being contained in the surrounding conically shaped spaces, a large quantity of this air is borne along with the gases, through the nozzles, the mixture of gases and air being discharged4 into the open atmosphere. A strong vacuum is being created within the spaces surrounding these nozzles, which in turn causes a strong suctionA of air through openings 10 (Figs. 1 and 2) and through the conductor, as well as through the additional openings 13 and 14. Cooling-air may also be drawn'in through openings 42 and .43 within the gun-chest,- (Flgs. 11, 13 and 14) as previously explained. From Figs. 3 and 4 which show more clearl the action of my devices, it will be seen, t at nozzle 2 is closed at first when a shot is beingfired, air therefore is being carried or borne in through nozzle 3, through friction being created between the gases and the air,.the air being condensed or compressed within nozzle 3 and forming an outer cone-shaped cover, surrounding the main body of gas. It will be understood, that the energy, being used up, for moving and for condensing gr compressing the air, is being furnishe expansion of the high pressure exhaustpowder-gases, which latter rush out mainly through the center portion of the cone and which continue, at the center, to exert a strong propulsive pressure on the ro'ectile, after the latter has emerged from the arrel, as is` well known. At the same time, the gases expand sidewise or in radial direction, advancing in the shape of a cone, gradually increasing in diameter. The object of condensing or compressing air, or a mixture of the latter with a portion of the gases, within nozzle 3, is to form againa compact outer surface of the streamof gas and air, rushing from the latter nozzle, capable of carrying along air from the outer a1r cone, surrounding nozzle 4, condensing and compressing again the air last drawn in, and so on. As

the surrounding air-cone is getting larger 1n diameter, the friction surface between the gas or mixture and between the air, in'

creases more and more, and as the speed of the gases decreases, the time being rovided for the acceleration of the surroun ing air increases. While the amount of air, being borne or drawn into the nozzles, is not exactly proportional to the frictional surface, the volume of air, being sucked or drawn into the nozzles, is a function of the frictional surface. The'volume of cooling air being sucked through the conductor, is therefore ,greatly increased, by using a plurality of nozzles, the latter successively increasing in size or capacity as shown. It will also be understood, that unless a certain degree of compactness is maintained in the outer conical surface of the exhaustpowder-gases or mixture, violet whirling action is created within the nozzles, whereby the flow of the incoming cooling-air, is decreased or prevented. Again, if a plurality of ejector nozzles are used successively, a .greater amount of kinetic energy is being developed, as a result of greater possible total expansion in successive steps, this kinetic energy being consumed in accelerating the speed` and com ressing the lar volume of cooling-air. he total loss 1n useful energy is very small, because a part of the energy would ordinarily be wasted by radial expansion, if the gases rush directly into the open air. For allthese reasons, a plurality of successive nozzles produce a far more efficient cooling of the barrel, but a plurality of nozzles of a character as shown erein has not been used heretofore for producing cooling air currents for cooling rapid fire-guns or the like.

The advanta es in using a. plurality of successive nozz es, each successive nozzle having a greater capacity or larger internal diameter than the preceding nozzle, as

explained. In ordinary guns, wherein gases enter directly into the open atmosphere, the gases normally expand, forming a cone, increasing in dlameter, its walls forming a small angle to the axis. 'The successive nozzles should be of relatively increasing calll) ' shown in my drawings, will now be further If -this stream is artl breaking' u violent whirling is plPoducd in the suriiounding air spaces, wherebyaxial cooling air currents are greatly reduced or weakened. One of the main objects of the invention is to produce as strong axial cooling currents as possible, and for this reason it is important, that the successive nozzles are of such relatively increasing ca acity, that unnecessary back pressure as we as whirling are avoided.

Another feature in applicants device which is of advanta and novel, is, that all nozzles are cooled th from without and within by the cooling air currents. This is important because the powder gases wouldotherwise uickly burn the nozzles.V

It shoul be explained, that the expansion nozzle 5, has primarily the object, of permitting further expansion of the outrushin mixture of gas an air, for the purpose o reducing `the noise of the exhaust as much as possible. In view of the large volume of air bein mixed with the gases, smoke is also muc decreased. The holes 33 in the ex ansion nozzle, increase the suction of air st' more and permit the ra id ow of cooling air to become more stea y, reducing momentary back-pressure and whirling, which would otherwise be created between shots and which would reduce the flow of v cooling-air, which in turn would reduce the eliciency of the riflev or gun.

Some further explanation is required reding the actionof my improved Vrecoil dgice. The instant, the shot has left the barrel, lthe exhaust owder-gases rush through the nozzle 2.

ince, however, the

Youtlet of nozzle 2 is made somewhat small,

the gases which'rush out, expan slightly radially, are stowed or penn up,. to

' some extent, within the nozzle 2, causing v momentarily a strong back-pressure. It

will be seen, that the member 17, at this moment, keeps the rear portion or end of this nozzle closed, the gases therefore are exerting'momentarily a power-ful pressure on the member 17, whereb the latter and the barrel', are vvery quic ly thrown backwards, from their position ofrest, '(Fi 3) until reach the potion shown `in ig. 4. It be understood, that, while the barrel moves and before it reaches the tion shown in Fig. 4, the main body of t 1 e: has already reached the open air an the back-pressure is entirely relieved. Asthe opening between the members 17 and 2 increases, the latter member or nozzle 2 begins to actas an ejector nozzle. When the member or nozzle is fully opened, the exhaust has entirelyv p out, and as a rev 'sult of the large momentum of the 'stream of cooling air within the conductor etc., the

cooling-air passes easily around the rounded outer portion of the member 17 land through 4nozzle 2, cooling it now from within and creating a strong suction at the barrel outlet',v

at the moment when the spent cartridge is v rel and member 17 are quickly returned tov their position of rest, by means of a spring or an other known means. When the member 1 and the barrel reach their position of rest (Fig. 3) the gun has been reloaded and the same motions of the said parts successively take place, and so on.

As mentioned before, the lthin lines and arrows represent the flow of the air, the

Athick line and arrow represents the ilow of the powder gases and the dotted lines and arrow represent leakage of exhaust powder gases through the annular space 18, 'being provided between the members 17 and 2. It is advisable to guide the member 17 accurately, concentrically to the member or nozzle 2, thus permitting the annular space 18 to be made small. The face 19 may bebroken or rilled as shown in Fi 7 and 8, in order to reduce whirling witlnn the nozzle 2 and in order to produce a maximum of recoil. The leakage may be somewhat reduced by such rills or by a broken or rough surface 19. My recoil device can be made to act las fast as desired, as stated heretofore, by changing the opening of the nozzle 2. My recoil device consumes only a very small amount of the useful energy ofthe exhaustpowder-gases, at any rate not more than is at present being consumed with existing recoil devices.

My recoil device isv an almost' necessary part in my system of air-cooled gun, or more correctly, lmy air-cooling system is a necessary-adjunct` if my improved recoil device is used for air-cooled guns. The device pref- In shortly g'utlnie advantages of lmy air-cooled machine or rapid-lire-gun, as

compared. with water-cooled guns, 1t may fire as rapidly as the latter, when the watercooled guns operate under favorable conditions. My gun may be tired as rapidly for as long series of shots as water-cooled guns, requiring no carrying of cooling medium, and no stops for replenishing the cooling medium, and no attention whatsoever to the cooling medium, the cooling system being very simple, nothing to get out'of order; all time may be concentrated on getting munition and operating the gun. It has always maximum efficiency, is always ready. There is no steam betraying position, less smoke, and less noise.` It is lighter and more easily handled and transported than water-cooled guns. The barrel 1s Well scavenged and intepally cooled; very accurate aiming is poss1 e.

As compared with existing air-cooled rifles, my gun may re several times as rapid if prolonged periods of firing are required.

Having thus explained my invention, and the advantages thereof, I claim:

1. In a machine gun or the like, a barrel, a plurality of gas ejector nozzles, being arranged successively and adjoiningly to the outlet of said barrel, each successive one of said nozzles having a larger capacity or internal diameter than the preceding one of said nozzles, said nozzles being adapted to produce strong cooling air currents while exhaust powder gases are passing through the same, means, employing said currents for cooling said barrel.

2. In a machine gun or the like, a barrel, a plurality of gas ejector nozzles, being arranged successively and adjoiningly to the outlet of said barrel, each successive one of said nozzles having a larger capacity or internal diameter than the 'preceding one of said nozzles, said nozzles being adapted to produce strong cooling air currents while exhaust powder gases are passing through the same, means, employing said currents for cooling said barrel and for cooling said nozzles internally and externally.

, 3. In a machine gun or the like, a barrel, a plurality of gas ejector nozzles, being arranged successively and adjoiningly to the outlet of said barrel, each successive one of said nozzles having ..a larger capacity or in ternal diameter than the preceding one of said nozzles, said nozzles being adapted to produce strong cooling air currents while exhaust powder gases are passing through the same, an air conductor surrounding said barrel, cooling air space being provided between said barrel and conductor, said space communicating at one end of said conductor with cool air of the atmosphere and at its other end with said1 nozzles.

4. In a machine gun or the like, a barrel, a plurality of gas ejector nozzles, being arranged successively and adjoiningly to the outlet ofsaidbarrel, said nozzles being adapted to produce strong cooling air currents, while exhaust powder gasesv ,are passmg through the same, an air conductor surrounding said barrel and nozzles, cooling air space being provided between said barrel and nozzles and conductor respectively, said space communicating at one end of sald conductor `with cool air of the atmosphere "zo I and at its other end with said nozzles, said currents cooling said barrel and cooling said nozzles from within and without.

5. In a machine gun or the like, a barrel, a plurality of gas ejector nozzles, being arranged successively and adjoiningly to the outlet of said barrel, each successive one of said nozzles having a larger capacity or internal diameter than the preceding one of said nozzles, said nozzles being adapted to produce strong coolingair currents while exhaust powder gases are passing throu h Vexhaust powder gases are passing through the same, an air conductor surrounding said barrel, cooling air space being provided between said barrel and conductor, an outer cover surrounding said conductor, providing cooling air space between said cover and conductor, said respective spaces communicating at one end of said conductor and cover,respectively, with cool air of the atmosphere and at the other respective ends with said nozzles.

7. In a machine gun or the like, a barrel, one or more ,gas ejector nozzles being arranged successively and adjoiningly to the outlet of said barrel, an air expansion nozzle being placed adjacently to one of the said ejector'nozzles, slots or openings being provided in saidexpansion nozzle, said nozzles being adapted to produce strong cool- Y ing air currents while exhaust powder gases are passing through the same, means, employing said currents for cooling said barrel.

8. In a machine gun or the like, 'a' barrel, a plurality of gas ejector nozzles, being arranged successively and adjoiningly to the outlet of said barrel, each successive one of said nozzles having a larger capacity or internal diameter than the preceding one of said nozzles, said nozzles being adapted t0 produce strong cooling air currents while exhaust powder gases are passing through the same, an air conductor surrounding said barrel, cooling air space being provided between said barrel and conductor.

l9. In a machine gun or the like, a barrel, two members, the one of the said members being placed movably, adj accntly to the outlet of said barrel, the other one of the said members being arranged, adjoiningly to said movable member, the saidmembers cooperating, momentarily creating backpressure of the exhaust powder gases when a shot is being fired, and whereby the said movable member receives a quick movement, increasing recoil, means returning said movable member to its osition of rest before the next shot is being red, vthe one of the said memy bers acting successively andintermittently,

first increasing recoil and secondly as gas ejector nozzle, in the latter case producing suction and cooling air currents through the action of the exhaust powder gases passing through said nozzle, one or more .gas ejector no les being arranged adjoiningly to said m bers, sald latter nozzle or nozzles havi a larger internal diameter or diameters tha said member and said nozzle or nozzles being adapted to increase suction and coolair currents, means, emplo said currents for cooling said barre 10. In a machine gun or the like, a barrel, two members, the one of the said members being placed movably,v adj acently to the outlet of said barrel, the other one of the said members bein arranged, adjoiningly to said movable mem r, the said membersl cooperating, momentarily creating backpressure ofthe exhaust powder gases when a shot is being fired, andwhereby the said movable member receives a quick movement, increasing recoil, means returning said movable member to its position of rest before the next shot is being fired, the one of the said members acting successively and intermittently, iirst increasing -recoil and secondly as gas ejector nozzle, in the latter case pro-.

ducing suction and cooling air currents through the action of the exhaust powder gases passing through said nozzle, one or more gas ejector nozzles being arranged adjoiningly to said members, a gas expansion nozzle being arranged adjoiningly to said nozzles, each successive nozzle havin a larger'internal diameter than its pre 'ng nozzle, said nozzles being adapted to increase suction and cooling air currents, means, employing said currents for cooling said barrel.

11. n a machine gun or the like, a barrel, a member being placed movably, adjacently to the outlet of said barrel, means, momentarily creating backpressure` of the -exhaust powder gases while a shot is being fired and -whereby said member receives a quick movementz means, returning said member to its miltlon of rest before the next shot is being one or more air 'ejectornzzles being arranged adjoiningly to the outlet of said barrel, and being adapted to produce strong suction and cooling air currents through the action of the exhaust powder Vgases passing through said nozzle or-nozzles, means, em ployin said currents for cooling said barrel. 12. n a machine gun or thelike, a barrel, a member being placed movably, adjacently to the outlet of said barrel, means, momentarily creating backpressure of the exhaust powder gases while a shot is being fired and whereby said member receives a quick movement, means, returning said member to its Eosition of rest before the next shot is bein red, said member acting alternate] an intermittently, first, increasing recoi and secondly, asV gas ejector nozzle, means, comprlslng one or more gas ejector nozzles in addition to said member, whereby strong suctlon and cooling air currents are being .created within said space, through the action of the exhaustpowder gases passing through saidnozzle or nozzles.

13. In a machine gun or the. like, a barrel, two members, the one of the said members being placed movably, adjacently to the outlet o said barrel, the other one of the said members being arranged, adjoiningly to said movable member, the 'said members cooperating, momentarily creating back-pressure of the exhaust powder gases when a shot is being fired, and whereby the said movable member receives a quick movement, increasing recoil, means returning said movablemembe'r to its position of rest before the next'shot is being fired, the one of the said members acting successively and intermittently, first increasing recoil and secondlyr as gas ejector nozzle, in the. latter case producing suction and coolin air currents through the action of the e aust powder gases passing through said nozzle, means, employing said currents for cooling said barrel. Y

14. In a machine gun or the like, a barrel, two members, the one of the said membersbeing placed movably, adjacentljto the outlet of said barrel, the other one'of the.

said members bein arranged2 adjoiningly to said movable mem r, the sald `members cooperating, momentarily creating backpressure of the exhaust powder gaseswhen a shot is being fired, and whereby the said movable member receives a quick movement,

increasing recoil, means returning said movable member to its position of rest before Vthe next shot is being tired, the one of the said members acting successively and intermittently, first increasing recoil and secr ondly as gas ejector nozzle, in the latter case producing suction and cooling air currents through the action of the exhaust powder gases passing through said nozzle, one or more gas ejector nozzles being arranged adjoiningly to said members thereby mcreasing the suction and cooling ,air currents,

'III

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means, -employing said currents for cooling said barrel.

15. In a machine gun or the like, a barrel, a member bein placed movable, adjacently, to the outlet o said barrel, means, momentaril creating pow er gases while a shot is being tired, and whereby said member receives a quick movement, increasing recoilz means, returning said member to its posltion of rest before the next shot is being fired, one or moreair ejector nozzles being arranged adjoiningly to said outlet, in such manner,- that strong suction and cooling -air currents are being created through the action of the exhaust powder gases passing through said nozzle or nozzles, means, employing said currents for cooling said barrel, and means, momentarily creating suction at said barrel outlet for the purpose of cooling and cleaning said barrel internally.

16. In a machine gun or they like, a barrel, an air conductor surrounding said barrel and an outer cover surrounding said conductor, providing cooling air spaces between the said barrel and conductor and outer cover respectively, one or more gas ejector nozzles being mounted ad'oinin 1y to the outlet of said barrel, sai con uctor and outer cover being at one of their respective ends in direct communication with the cool air of the atmosphere and communcatin at v their other respective ends witheach ot er and with said nozzle or nozzles, the exhaust powder gasespassing through said 'nozzle or nozzles, creating strong suction and cooling air currents within the said spaces.

17. In a machine gun or the like, a member, being mounted movably wand adjoiningly to the outlet of said barrel, means, momentarily creating backpressure of the exhaust owder ases while a shot is .being fired, an where y said member receives a quick movement, increasing recoil, means, returning said member to itsA position of rest before the nextshot is beinguired, an air conductor surrounding said backpressure of the exhaust' a barrel,

rrel, an4

outer cover surrounding said conductor, providing coolin air space between said conductor and said outer cover, means, comprising one or 4more gas ejector nozzles, whereby strong suction and cooling air currents are being created within said space through the action of the exhaust powder gases gassing through said nozzle or nozzles,

18. n a machine gun or the like, a barrel, cooling webs on sai barrel, an air conductor surrounding said barrel and said webs, an outer cover surrounding said conductor, providing cooling air spaces between said arrel and conductor and outer cover, respectively, bein mounted adjoiningly to the outlet of saidgbarrel, thev exhaust powder gases passing through said nozzle or nozzles, producing strong suction and air currents within the said s aces, for the purpose of cooling said barre, conductor and cover.

19. In a` machine gun or the like, a barrel, aplurality of air ejector'nozzles arranged adjoiningly to barrel, an air expansion nozzle being placed adjacently to said ejector nozzle, slots or openings being provided in said expansion nozzle, said ejector nozzles and expansion Vnozzle being adapted to produce stron suction and'coolin -air currents throug the action of the ex aust powder gases passingl through said nozzles, means, employing sai air currents for coolmg said barrel.

20. In a machine gun or the like, an air ejector nozzle bem arranged adj omingly to the outlet of sai barrel, an air exsaid e'ector nozzles, slots or openings being provi ed in said expansion4 nozzle, said ejector nozzle and expansion nozzle bein adapted to produce strong suction and coo g air currents through the action of the exhaust powder gases passing through said nozzles,

means employlng said air currents for cooling said barrel.

c H. POHLMANN.

one or more gas ejector nozzles,

the outlet of sai a barrel,

lpansion nozzle being placed' adjacently to 

